A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
A conventional lithographic apparatus, typically comprises a support structure (also referred to as a mask stage) that is provided and constructed to support the patterning device. Similarly, the apparatus comprises a substrate table which is constructed to hold the substrate. Conventionally, the mask is clamped by vacuum to the mask stage chuck which is fixedly held on the mask stage. The maximum acceleration of the patterning device or mask is limited in conventional lithographic apparatuses by the vacuum pressure, the vacuum clamp area, friction between the mask and the chuck and the mask mass, in order to prevent the mask from micro and macro slip. The support structure and substrate table are movable in a scanning (Y) direction. In particular, at the beginning and towards the end of a scanning cycle, the support structure and substrate table are subject to acceleration and deceleration forces to reach a scanning velocity and to come to a standstill, respectively. In order to increase the throughput of the machine, i.e. the number of substrates that can be processed with the lithographic apparatus in a certain time, it is desirable that the support structure and substrate table reach and decelerate from the scanning speed as quickly as possible. To achieve this, the acceleration and deceleration of the support structure and/or substrate table must be increased. It has been found, however, that this results in an increased inertia force to the mask and/or substrate, and an increased risk of micro and macro slip of the mask and/or substrate. This leads to imaging errors. In particular, with respect to the mask stage when it is subject to increased inertia forces, conventional vacuum clamps may not be able to clamp the mask with sufficient force.